I got PostgreSQL from here.
Since I'm on 10.7 OS X, I'm having problems.
I want to uninstall the software I got from enterprisedb.
Ask Different is a question and answer site for power users of Apple hardware and software. It only takes a minute to sign up.Sign up to join this community
There is a one-click uninstaller that removes everything except the data director and user account. The default data directory is /Library/PostgreSQL/$VERSION/data, so rm -rf that directory (or wherever you instructed the installer to create it).
To remove your postgres user (assuming it is named 'postgres'), first list your users to verify that the user 'postgres' and group 'postgres' are what you expect: (just a safe check) before deleting anything.
sudo dscl . -read /Users/postgres
sudo dscl . -read /Groups/postgres
Look for the "real name" field, to ensure that it matches the version of the db you are removing.
Then remove the user and groups:
sudo dscl . -delete /Users/postgres
sudo dscl . -delete /Groups/postgres
Obviously, be careful when using sudo.
The uninstallation instructions are at the bottom of the installation guide linked from that download page.